Iacobus Leodiensis [Iacobus de Montibus, Iacobus de Oudenaerde]

2. Works.

(i) The Ordinary of the Mass.

(ii) The Proper of the Mass.

(iii) Motets.

(iv) Songs.

Isaac, Henricus, §2: Works

(i) The Ordinary of the Mass.

Isaac wrote 36 mass cycles that are known to survive today, as well as a handful that seem to have been lost. He also composed 13 independent settings of the Credo. His 16 masses based on borrowed melodies are comparable in number, quality and variety to those of Josquin, Obrecht or Agricola, but unlike them he composed at least 20 further cycles based on the corresponding plainchant of the Ordinary of the Mass, all but one of these for alternatim performance. Together with his cycles for the Proper of the Mass, Isaac’s music for the Ordinary was his most characteristic and influential contribution to the music of his time.

Isaac’s masses on borrowed melodies are difficult to date or localize. Source transmission and some slight documentary evidence suggest that eleven cycles had been composed by about 1492: ‘Argentum et aurum’, ‘Chargé de deul’, ‘Comme femme’, ‘Een vrolic wesen’, ‘Et trop penser’, the lost ‘J’ay pris amours’, ‘La Spagna’, ‘Quant j’ay au cueur’, ‘Salva nos’, ‘Une musque de Biscaye’ and the four-voice Missa ‘Comment poit avoir joie’. Four or five others may belong to the following decade: the six-voice Missa ‘Wolauff Gesell’ (after c1496), the Missa carminum (after c1496), ‘Virgo prudentissima’ (possibly performed 1503) and possibly ‘T’meiskin was jonck’. The mass ‘La mi la sol’ is based on a motet composed in 1502. The Missa ‘Misericordias Domini’ is also late, but it appeared in the company of four early masses in Petrucci’s Misse Henrici Yzac (1506).

Seven of Isaac’s masses are based on polyphonic chansons from the Franco-Flemish tradition: the rondeaux Comme femme (Binchois), Quant j’ay au cueur (Busnoys) and Een vrolic wesen (Barbireau), the virelais Chargé de deul (anon.) and Et trop penser (Bosfrin ?= Josquin) and the Dutch song T’meiskin was jonck (Obrecht). A mass by Isaac, now lost, on the well-known rondeau J’ay pris amours (anon., ?by Caron) was mentioned in 1490. Monophonic secular tunes include the internationally known basse danse La Spagna, the chanson rustique Une musque de Biscaye (this bears no relation to Josquin’s canonic song setting or to his mass on the same tune) and the popularizing song Comment peut avoir joie. The last also carried the German words Wohlauf Gesell, von hinnen; Isaac’s four-voice mass setting existed before 1490 and probably implies the French text, but the six-voice mass has the German title in its unique source, an Innsbruck manuscript (D-Mbs Mus.ms.3154). The Missa carminum strings together a number of German popular songs in the manner of Obrecht’s and Pipelare’s Missae carminum on French and Dutch chansons and an older Austrian tradition of Liedermessen.

Isaac used multiple sacred cantus firmi (a technique familiar in the Low Countries and in Germany) in the Missa ‘Salva nos’, which is chiefly based on an antiphon but also quotes several short invocations from the chants of the Mass. Three sections (the second Kyrie, ‘Cum Sancto Spiritu’, the second ‘Osanna’), based on the plainchant phrase ‘et requiescamus in pace’, were incorporated into Isaac’s motet Quis dabit capiti meo aquam? on the death of Lorenzo de’ Medici; probably both the mass and the motet were intended for the funeral ceremonies. A mass for the Assumption of the Virgin Mary was performed at Innsbruck on 26 September 1503 in a meeting of the Imperial and Burgundian chapels; this may have been Isaac’s six-voice Missa ‘Virgo prudentissima’, which is given the rubric ‘de assumptione beate marie virginis’ in a Burgundian choirbook (B-Br 6428). Isaac’s mass is related neither to his own four- and six-voice motets nor to Josquin's similarly titled O Virgo prudentissima (on a poem by Poliziano). Likewise, Isaac’s mass ‘Argentum et aurum’ shares only its cantus firmus with his motet, probably composed earlier. Staehelin (1977) identified a musical antecedent for the Missa ‘Misericordias Domini’ in the anonymous frottola In focho, in focho la mia vita passa, suggesting that Isaac’s intermediate model was a lost motet by Mouton, based on the frottola. The only demonstrable case in which Isaac elaborated one of his own shorter works into a mass is the Missa ‘La mi la sol’, based on his ‘motet’ composed in Ferrara in 1502.

Isaac employed all the formal and technical devices for which the Franco-Flemish mass composers of his generation are celebrated. Manipulation of the cantus firmus is rare: retrograde occurs in the second ‘Osanna’ of ‘Argentum et aurum’ and in the ‘Et incarnatus’ of ‘T’meiskin was jonck’; a notable example of mensural artifice is seen at the beginning of ‘Argentum et aurum’, where all the voices sing the same melody at different levels of duration in exclusively dotted notes. Isaac used canon less frequently than Josquin (see the masses ‘Comme femme’, ‘Comment poit avoir joie’ and elsewhere), but he often conducted the cantus firmus in canon. ‘Parody’ (borrowing several voices simultaneously from a polyphonic model), paraphrase, migration of the cantus firmus between the voices and ostinato are frequently found. Isaac avoided large-scale constructive devices, but achieved coherence through modal unity and the pervasive use of borrowed material. The texture of his counterpoint varies greatly: imitative writing in three or four voices predominates, but may be coordinated with ostinato or, very often, a ‘pedal-point’ texture with the cantus firmus in long notes. A simple chordal declamation or rapid parlando is occasionally found in the early masses, but on the whole there is more syllabic word-setting in the later works. Like Obrecht, Isaac favoured repetitive and sequential passages, which might result in static harmonies when the motivic substance is triadic as in the masses ‘Comment poit avoir joie’, ‘Argentum et aurum’, ‘Et trop penser’. The textures of the last two are playfully ornamented and patterned; many sections resemble textless ‘instrumental’ fantasias. In the Missa ‘La mi la sol’ an eight-note ostinato is treated with great melodic versatility and modal coherence.

Isaac’s masses, to a significantly greater extent than those of Josquin or Obrecht, were used as quarries for secular music-making. Three-voice sections in particular circulated widely, sometimes appearing with their original titles (e.g. the ‘Benedictus’ from Missa ‘Quant j’ay au cueur’ or the Christe from ‘Chargé de deul’), sometimes with new words or with no words at all. Isaac may have deliberately encouraged secular use of these mass sections by composing them in a style resembling that of the chanson. The song settings T’meiskin was jonck and Een vrolic wesen were mistakenly ascribed to Isaac, apparently because he wrote masses based on them, while one of his settings of Fortuna desperata was labelled ‘Sanctus’ as if it had been extracted from a mass on that tune. In the Missa ‘La Spagna’, the three-voice second Agnus Dei gives the borrowed melody complete in the bassus, all in perfect longs; a separate copy in an early Italian source has been regarded as the model for the mass, though such a strict technique would be atypical for a self-contained composition. Some masses employed an extremely simple mode of recomposition: the six-voice Missa ‘Wolauff Gesell’ largely re-uses the counterpoint of the four-voice Missa ‘Comment poit avoir joie’ on the same tune, and the ‘motet’ La mi la sol is incorporated en bloc into the Credo of the mass of that name.

During his Habsburg service from 1496, Isaac contributed largely to the genre of mass cycles based on the corresponding chants of the Ordinary of the Mass, composed for particular categories of feasts such as apostles, the Virgin Mary and so on. Most of the plainsong melodies used by Isaac are found in the printed Graduale pataviense (Vienna, 1511), a source approximating the usage of the Imperial chapel (see §2(ii) below). Although individual mass sections based on the chant of the Ordinary were as common in central Europe around 1450–90 as they had been in England and France somewhat earlier, few composers before 1500 wrote complete cycles (Martini, Missae dominicalis and ferialis; Urrede (Wreede), Missa de Beata Virgine; La Rue, Missae de Beata Virgine, ferialis, paschalis and pro defunctis; Agricola, Missa paschalis on ‘German’ chants). With at least 20 cyclic settings, Isaac monumentalized a regional tradition formerly with little prestige and elaborated it in the most modern styles.

Except for the Missa ferialis, all Isaac’s plainchant masses were designed for alternatim performance: alternate verses were composed in vocal polyphony, leaving the others to be chanted or played on the organ. In one source Isaac’s works are called ‘Missae ad organum’, and there is evidence that alternation between vocal polyphony and organ versets was the Imperial chapel’s practice (see Mahrt), which Maximilian may have brought from Flanders. It appears that six-voice alternatim masses were among the first works Isaac composed for Maximilian’s chapel. A chapel choirbook copied about 1510 (D-Mbs 31) preserves the six-voice Missae solemnis, de Beata Virgine and de apostolis together with the six-voice cantus-firmus mass ‘Virgo prudentissima’. A six-voice alternatim Missa paschalis, in a somewhat different and possibly earlier style, occurs in Netherlandish and central-German sources. Isaac also composed five-voice cycles for the same four feasts as well as for martyrs, confessors and virgins. These seven masses survive uniquely in an important choirbook of the Bavarian ducal chapel (D-Mbs 3), copied by Ludwig Senfl from Imperial exemplars. A further five-voice Missa de Beata Virgine is independent from the others; its plainchants for the Kyrie and Gloria are found only in graduals from Augsburg and Basle.

Isaac composed four-voice alternatim Missae solemnis, paschalis, de Beata Virgine, de apostolis, de martyribus and de confessoribus; probably all later works. Together with the through-composed Missa ferialis, they appear as a set in several sources. These works could be used by smaller choirs for many ritual occasions and circulated much more widely than the five- and six-voice cycles. Five of the four-voice masses (all but the Missae de Beata Virgine and ferialis) were printed in the third volume of the Choralis Constantinus (1555), with an additional alternatim Credo for all but the Missa de confessoribus. A distinct alternatim Missa paschalis ad organum is scored for lower ranges and may have served a special purpose. A doubtful four-voice Missa de Beata Virgine incorporates material from the authentic six-voice cycle, but its Sanctus and Agnus Dei are probably by a different hand. Isaac also composed a three-voice Missa de Beata Virgine, but it is doubtful whether the existing work is by him or Senfl.

A Bavarian chapel manuscript (D-Mbs 53) presents 13 four-voice plainchant-based Credos by Isaac, which complement the four-voice alternatim masses. Their style is often surprisingly simple, perhaps reflecting popular appreciation of the chants. Only the twelfth of these Credos is an early work (?c1480-90), based on a number of borrowed chants all connected with feasts of the clergy and Eastertide processions.

Isaac’s alternatim mass settings display a vast musical panorama of Mass plainchant. All the cantus-firmus procedures of the time are present, although paraphrase, migration, transposition and ornamentation predominate over scaffolding or canon techniques. The chant melody often appears in imitation between two voices, especially in the six-voice works. The modes, ranges and melodic styles of the plainchant influence the polyphonic settings and their degree of musical unity. Skilful organ versets based on the alternate verses would have highlighted Isaac’s own contribution. The forms of his alternatim masses are episodic and narrative – sometimes epigrammatical in the shorter verses – rather than architectural.

Isaac, Henricus, §2: Works